Essay about The Immune System

1693 Words Aug 8th, 2016 7 Pages
The purpose of the immune system is to defend the body against any foreign invaders that might do the body harm by using a series of immune responses to prevent the entry or survival of any foreign body. The human immune system uses three types of responses: barriers, nonspecific defenses, and specific defenses. Barriers and nonspecific defenses are innate or rather they are the defenses humans are born with while specific defenses are acquired throughout our lifetime. The immune system is also meant to destroy any hazardous cells like any infected with a virus or any cancerous cells. It is composed of the thymus, the spleen, the lymph nodes along with a variety of cells like leukocytes and antibodies.
The immune system provides immunity against specific pathogens which can be gained passively or actively. Passive immunity is when someone gains resistance to a disease without actually coming in direct contact. The most common way people gain passive immunity is when they are infants and antibodies are transferred through breast milk. The most common form of gaining protection against pathogens is through active immunity. Vaccines are a form of acquiring active immunity because the patient is injected with a weakened form of the virus. This results in antibodies being produced and memory cells being formed without the virus causing an illness. The most common form of active immunity is when someone gets infected with a pathogen and while their body is fighting it off memory…

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